Colour theory describes harmonic relationships between colours based on their positions on the colour wheel. Complementary pairs sit opposite each other (maximum contrast); triadic schemes use three equally-spaced colours; analogous schemes use adjacent colours for a natural, cohesive look. This generator applies these formulas to any base colour, instantly producing a palette with copyable values.
Complementary: base colour + colour directly opposite (180°). High contrast, vibrant — good for call-to-action buttons against brand colour. Analogous: three colours spaced 30° apart — natural and serene. Good for backgrounds and neutral palettes. Triadic: three colours 120° apart — balanced yet colourful. Split-complementary: base + two colours 150° away — softer than complementary, more dynamic than analogous. Tetradic: four colours 90° apart — maximum variety; usually one colour dominates.
Colour theory is a body of principles for combining colours aesthetically and meaningfully. It includes the colour wheel, colour harmony models, and the psychological associations of different hues — foundational knowledge for UI design, branding, and visual communication.
There is no universal answer, but common approaches: pick one strong accent colour and pair it with a neutral background (white, off-white, or dark grey). Use one analogous or complementary colour for secondary actions. Limit to 3–4 colours in total.
Test every foreground/background pair with the Color Contrast Checker. At minimum, text colours must achieve a 4.5:1 contrast ratio against their backgrounds (WCAG 2.1 AA).
HSL (Hue, Saturation, Lightness) maps directly to the colour wheel. Hue is the angle (0–360°), making it trivial to compute colour harmonies by adding 60°, 90°, 120°, etc. RGB arithmetic would give the same results but requires much more complex intermediate calculations.
See also the Color Mixer, Color Contrast Checker, and the CMYK Converter.